Air Fuel Ratios (AFR)

Discussion in 'Technical' started by Jinxed, Sep 13, 2016.

  1. Jinxed

    Jinxed Moderator

    Turbo z32.

    What AFR would be considered "normal", and what would be rich and lean

    looking for the number AFR 12:1 or whatever they are meant to be

    aware that its not set in stone just looking for a indication of where it should be......
     
  2. rollin

    rollin First 9

    idle and cruis 14.5 to 15

    wide open 11.5 to 12.8

    closed throttle decel could go 25 +

    these are ball parks
     
  3. Jinxed

    Jinxed Moderator

    so is lean a higher number or a low number.

    ie is 10 rich? or is 15 rich?
     
  4. lean is lower
     
  5. zx299

    zx299 Well-Known Member

    Lean is HIGHER......

    An AFR of 15 is leaner than an AFR of 12

    An AFR of 10 is rich as buggery (almost throwing fuel out the exhaust)
     
  6. Shane001

    Shane001 Well-Known Member

    zx299 is correct. 15 is lean. 10 is rich.

    You want to target around 11.5-12 at WOT full boost.

    Bear in mind we're talking AFR's which are fuel specific, the above is for standard fuel, not ethanol blended fuel.

    These days it's better to talk in lambda. Lambda is the same regardless of fuel.

    Google is your friend :p
     
  7. MagicMike

    MagicMike Moderator Staff Member

    We are talking air : fuel ratio. Exactly that. Ratio of air per part of fuel.

    Stoich for petrol is 14.7 : 1. Richer means less air per part fuel ie 10 : 1. Leaner is more air per part fuel ie 17 : 1.

    Lambada reading of 1 is stoich for whichever fuel is used.
     
  8. AAU54U

    AAU54U Member

    I think max power is around 12.5 but for turbos they seem to like you to stick under 12 at WOT. I think a stock NA can run at 12.5 at WOT (I know someone running their NA at 13 at WOT).
     
  9. Bob Lloyd-Jones

    Bob Lloyd-Jones Oldreverbob

    Best results

    :br:Got my turbo to run best on a dyno with a fuel air mix of 12.1:zlove:
     
  10. SRB-2NV

    SRB-2NV #TEAMROB

    Depends on the engine and setup.
     
  11. ok thank you.
     
  12. This is why i dont build high hp cars. always more to learn.
     
  13. Jinxed

    Jinxed Moderator

    thanks all, much appreciated.
     

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